Renormalization Group Research Articles

Unveiling the potential of digital human avatars in modern marketing strategies

PurposeThis study aims to develop a theoretical framework that marketing practitioners and scholars can adopt to enhance their understanding of how firms can effectively deploy and use digital human avatars as part of their global digital marketing strategy. By doing so, we inform investors of ongoing digital transformations of marketing practices that will equip marketeers to provide scalable, tailored, reliable and relevant digital self-service interactions to users, consequently improving the user/customer experience.Design/methodology/approachThematic analysis was used to discover factors to enable the successful implementation of digital human avatars, drawing on in-depth interviews with fourteen executives of digital human avatars developer companies worldwide and analysis of ten podcasts and webinars with artificial intelligence (AI) experts.FindingsDigital human avatars revitalise the international dynamic marketing capabilities (IDMCs) of firms by integrating advanced technologies that transform user interactions, improve engagement and facilitate knowledge acquisition, dissemination and usage across various sectors and business units globally. This integration promotes a dynamic approach to international brands, customer relationships and marketing knowledge management capabilities, offering profound value to users and firms.Research limitations/implicationsOur first limitation is a lack of diversity in data sources. As digital human avatars are an emerging field, we had to limit our study to 14 experts in AI and 10 podcasts. While this method provides deep insights into the perspectives of those directly involved in the development and implementation of digital human avatars, it may not capture the views of end-users or consumers who interact with these avatars, which can be an avenue for further research. Our second limitation is the potential bias in the interpretation of our interview data and podcasts. This study’s approach to data analysis, where themes are derived from the data itself, carries a risk of subjective interpretation by the researchers. Future studies are encouraged to investigate the impact of digital human avatars across different organisational contexts and ecosystems, especially focusing on how these technologies are integrated and perceived in various international markets.Practical implicationsThe novel framework has direct implications for innovators and marketing practitioners who aim to adopt digital human avatars in their marketing practices to enhance the effectiveness of international marketing strategies.Social implicationsThe adoption of digital human avatars can alleviate loneliest elderly and vulnerable people by being a companion. The human-like characteristics can impact sense of presence and attachment.Originality/valueThe novelty of our study lies in exploring the characteristics of technologies and practical factors that maximise the successful adoption of digital human avatars. We advance and contribute to the emerging theory of avatar marketing, IDMCs and absorptive capacity by demonstrating how digital human avatars could be adopted as part of a firm’s global digital marketing strategy. We focus specifically on six dimensions: outcomes and benefits, enhancements and capabilities, applications and domains, future implications, foundational elements and challenges and considerations. This framework has direct implications for innovators and marketing practitioners who aim to adopt digital human avatars in their marketing practices to enhance the effectiveness of international marketing strategies.

Euclidean wormholes in holographic RG flows

Abstract We describe a one-parameter family of Euclidean wormhole solutions with the topology of a compact hyperbolic space times an interval in Einstein gravity minimally coupled to a massless scalar field in AdSd+1 commonly referred to as Einstein-dilaton gravity. These solutions are locally described by the same metric and dilaton profile as the single-boundary Janus domain wall solutions in the same theory which are usually studied in the context of holographic RG flows. The wormholes compute the averaged product of partition functions of CFTs on either boundary deformed by different marginal couplings to the scalar operator dual to the dilaton. We observe that the renormalised volumes of these wormholes increase monotonically with the difference in the marginal couplings on the boundary thereby showing that the pair of CFTs on the boundaries get increasingly decorrelated as the difference in the marginal couplings increases. We use the partition functions of the three-dimensional wormhole solutions to determine the variance of the OPE data of local operators between the marginally deformed 2d CFTs and quantify how the variance decays with the difference in marginal couplings. In addition, a family of wormholes sourced by a thin shell of dust determine how the variance of the matrix elements of the dual line defect decays with the difference in marginal couplings. Applying the GKPW dictionary to wormholes, we compute averages of integrated dilaton correlators treating the wormhole amplitude as a functional of the dilaton sources. We observe that the crossed two-point correlators with a dilaton insertion on either boundary decay monotonically with the difference in marginal couplings consistent with the observation that the CFTs increasingly decorrelate as the difference in marginal couplings grows.

Towards streamlined product information: reporting of transporter-mediated drug interactions.

The purpose of this study is to investigate the reporting of risks associated with transporter-mediated drug-drug interactions (DDIs) in medicinal product information and to identify suitable wording for future standardisation of summaries of product characteristics (SmPCs). The SmPCs of medicinal products approved in the European Union from 2012 to 2023 were screened for warnings on Organic Anion Transporting Polypeptide 1B1 and 1B3 (OATP1B1 and OATP1B3), and Breast Cancer Resistance Protein (BCRP). An in-house search engine for product information was used. Warnings were categorised into different DDI scenarios based on the SmPC texts. A total of 192 out of 859 approved medicinal products had SmPC text pertaining to OATP1B1, 1B3 and/or BCRP. The majority of products had text for all three transporters Most texts were located in SmPC Sect.5.2, followed bySect. 4.5. Numerous interaction-texts either concluded that the interaction lacked clinical relevance or lacked information on the clinical relevance of the finding. The highest number of SmPC texts indicating a clinically relevant interaction with outlined clinical consequences was found for BCRP. The article also presents SmPC texts for each DDI scenario, which the authors consider as examples of explicitwordings with actionable recommendations. A potential for improvement of SmPC text for transporter-mediated DDI was identified: Warnings without clinical relevance could be omitted, and some warnings with clinical relevance could be updated to provide actionable recommendations to the prescribers. A selection of unambiguous texts was identified as starting point to generate standard texts.

Marginal interaction test for detecting interactions between genetic marker sets and environment in genome-wide studies.

As human complex diseases are influenced by the interaction between genetics and the environment, identifying gene-environment interactions (G × E) is crucial for understanding disease mechanisms and predicting risk. Developing robust quantitative tools for G × E analysis can enhance the study of complex diseases. However, many existing methods that explore G × E focus on the interplay between an environmental factor and genetic variants, exclusively for common or rare variants. In this study, we developed MAGEIT_RAN and MAGEIT_FIX to identify interactions between an environmental factor and a set of genetic markers, including both rare and common variants, based on the MinQue for Summary statistics. The genetic main effects in MAGEIT_RAN and MAGEIT_FIX are modeled as random and fixed effects, respectively. Simulation studies showed that both tests had type I error under control, with MAGEIT_RAN being the most powerful test. Applying MAGEIT to a genome-wide analysis of gene-alcohol interactions on hypertension and seated systolic blood pressure in the Multi-Ethnic Study of Atherosclerosis revealed genes like EIF2AK2, CCNDBP1 and EPB42 influencing blood pressure through alcohol interaction. Pathway analysis identified one apoptosis and survival pathway involving PKR and two signal transduction pathways associated with hypertension and alcohol intake, demonstrating MAGEIT_RAN's ability to detect biologically relevant gene-environment interactions.

Simulating Real-Time Molecular Electron Dynamics Efficiently Using the Time-Dependent Density Matrix Renormalization Group.

Compared to ground-state electronic structure optimizations, accurate simulations of molecular real-time electron dynamics are usually much more difficult to perform. To simulate electron dynamics, the time-dependent density matrix renormalization group (TDDMRG) has been shown to offer an attractive compromise between accuracy and cost. However, many simulation parameters significantly affect the quality and efficiency of a TDDMRG simulation. So far, it is unclear whether common wisdom from ground-state DMRG carries over to the TDDMRG, and a guideline on how to choose these parameters is missing. Here, in order to establish such a guideline, we investigate the convergence behavior of the main TDDMRG simulation parameters, such as time integrator, the choice of orbitals, and the choice of matrix-product-state representation for complex-valued nonsinglet states. In addition, we propose a method to select orbitals that are tailored to optimize the dynamics. Lastly, we showcase the TDDMRG by applying it to charge migration ionization dynamics in furfural, where we reveal a rapid conversion from an ionized state with a σ character to one with a π character within less than a femtosecond.

Quantum wires with local particle loss: Transport manifestations of fluctuation-induced effects

We investigate the transport properties of a quantum wire of weakly interacting fermions in the presence of local particle loss. We calculate current and conductance in this system due to applied external chemical potential bias that can be measured in experimental realizations of ultracold fermions in quasi one-dimensional traps. Using a Keldysh field theory approach based on the Lindblad equation, we establish a perturbative scheme to study the effect of imbalanced reservoirs. Logarithmically divergent terms are resummed using a renormalization group method, and a novel powerlaw behavior for the conductance as a function of the potential bias across the wire is found. In contrast to the equilibrium case of a potential barrier in a Luttinger liquid, the conductance exhibits a scaling behavior, which depends on the interaction strength and on the loss probability. Repulsive interactions reduce the conductance of the wire while attractive interactions enhance it. However, perfect reflectivity and transparency are only reached in the absence of particle loss. Published by the American Physical Society 2024

Mapping a dissipative quantum spin chain onto a generalized Coulomb gas

An XXZ spin chain at zero magnetization is subject to spatially correlated baths acting as dissipation. We show that the low-energy excitations of this model are described by a dissipative sine-Gordon field theory, i.e. a sine-Gordon action with an additional long-range interaction emerging from dissipation. The field theory is then exactly mapped onto a generalized Coulomb gas which, in addition to the usual integer charges, displays half-integer charges that originate from the dissipative baths. These new charges come in pairs linked by a charge independent logarithmic interaction. In the Coulomb gas picture, we identify a Berezinsky–Kosterlitz–Thouless-like phase transition corresponding to the binding of charges and derive the associated perturbative renormalization group equations. For superohmic baths, the transition is due to the binding of the integer charges, while for subohmic baths, it is due to the binding of the half-integer charges, thereby signaling a dissipation-induced transition.

Superconductivity in the pressurized nickelate La3Ni2O7 in the vicinity of a BEC–BCS crossover

Ever since the discovery of high-temperature superconductivity in cuprates, gaining microscopic insights into the nature of pairing in strongly correlated systems has remained one of the greatest challenges in modern condensed matter physics. Following recent experiments reporting superconductivity in the bilayer nickelate La3Ni2O7 (LNO) with remarkably high critical temperatures of Tc = 80 K, it has been argued that the low-energy physics of LNO can be described by the strongly correlated, mixed-dimensional bilayer t–J model. Here we investigate this bilayer system and utilize density matrix renormalization group techniques to establish a thorough understanding of the model and the magnetically induced pairing through comparison to the perturbative limit of dominating inter-layer spin couplings. In particular, this allows us to explain appearing finite-size effects, firmly establishing the existence of long-range superconducting order in the thermodynamic limit. By analyzing binding energies, we predict a BEC–BCS crossover as a function of the Hamiltonian parameters. We find large binding energies of the order of the inter-layer coupling that suggest strikingly high critical temperatures of the Berezinskii–Kosterlitz–Thouless transition, raising the question of whether (mixD) bilayer superconductors possibly facilitate critical temperatures above room temperature.

Microwave Synthesis and Luminescence Efficiencies in Mixed-Ligand Europium Complexes.

The microwave-assisted methodology is now extended and fine-tuned for the synthesis of mixed-ligand europium complexes with an average reaction time of 12 min. Overall, 14 different complexes were synthesized to improve luminescence using our previously proposed strategy to boost luminescence through ligand diversification, specifically by applying it to quaternary europium complexes with at least one DBM (1,3-diphenylpropane-1,3-dionate) ligand. DBM is a strong absorbant of UV radiation that can dissipate energy through nonradiative channels; thus, it is a useful molecular scaffold for sunblockers and cosmetics. Accordingly, the following luminescent tetrakis and quaternary complexes were prepared: K[Eu(DBM)4], K[Eu(β)4], K[Eu(DBM)3(β)], K[Eu(DBM)2(β)2], K[Eu(DBM)2(β)(β')], and the fully mixed complex K[Eu(DBM)(BTFA)(TTA)(HFAC)], where β can be either BTFA (4,4,4-trifluoro-1-phenylbutane-1,3-dionate), TTA (4,4,4-trifluoro-1-(2-thienyl)butane-1,3-dionate), or HFAC (1,1,1,5,5,5-hexafluoropentane-2,4-dionate). For all the complexes, luminescence experiments were performed in chloroform and acetone solutions. Our findings confirm that mixed-ligand complexes exhibit superior quantum efficiencies compared to the average of their homoleptic counterparts. The presence of DBM in the complexes tends to dramatically increase the nonradiative decay rates of the solutions. Finally, we present formulae that provide a detailed understanding of the distinctive roles of each ligand and their relevant interactions in luminescence.

Acute phase responses in clinically healthy multiparous Holsteins with and without calcium dysregulation during the early postpartum period

Patterns of calcium dysregulation resulting in low total serum calcium concentrations (tCa) at 4 DIM, known as dyscalcemia, commonly occur in multiparous Holsteins. Dyscalcemia is associated with risk of disease, decreased production, and poor reproductive performance. Inflammation is well-documented early in lactation and is associated with similarly suboptimal outcomes. The acute phase response produces markers and mediators of inflammation; therefore, the objective of our case-control study was to evaluate postpartum patterns of 3 positive acute phase proteins in cows with and without dyscalcemia. We hypothesized that dyscalcemic cows would experience more activated inflammation than eucalcemic cows and that inflammation would precede dyscalcemia diagnosis. Multiparous Holstein cows at 2 commercial dairy farms in central New York were enrolled from a parent study based on tCa at 4 DIM, at a 2:1 ratio of eucalcemic (tCa >2.3 mmol/L; n = 32) to dyscalcemic cows (tCa <2.2 mmol/L; n = 16). Blood was collected 1 to 3 d before parturition and once every 24 h postpartum through 4 DIM. Samples were analyzed for 3 acute phase proteins, serum amyloid A (SAA), haptoglobin and lipopolysaccharide binding protein (LBP). Patterns of protein concentrations in blood over time were compared using linear mixed effects models including fixed effects of calcium status group, time, parity group, farm, relevant 2-way interactions, and the random effect of cow. Overall, dynamics of acute phase proteins showed that dyscalcemic cows experienced increased acute phase responses compared with eucalcemic cows, and that these responses preceded dyscalcemia diagnosis at 4 DIM. Dyscalcemic cows had elevated concentrations of SAA beginning at 2 DIM (eucalcemic: mean = 13.88 µg/mL, 95% CI = 11.34 to 16.99 µg/mL; dyscalcemic: mean = 32.95 µg/mL, 95% CI = 24.55 to 44.21 µg/mL). and continuing through 4 DIM (eucalcemic: mean = 8.14 µg/mL, 95% CI = 6.66 to 9.95 µg/mL; dyscalcemic: mean = 30.01 µg/mL, 95% CI = 22.60 to 39.83 µg/mL). Haptoglobin concentrations were also elevated in the blood of dyscalcemic cows from 2 DIM (eucalcemic: mean = 0.39 g/L, 95% CI = 0.31 to 0.49 g/L; dyscalcemic: mean = 1.11 g/L, 95% CI = 0.79 to 1.56 g/L) through 4 DIM (eucalcemic: mean = 0.27 g/L, 95% CI = 0.21 to 0.34 g/L; dyscalcemic: mean = 1.65 g/L, 95% CI = 1.19 to 2.28 g/L). Concentrations of LBP exhibited a different pattern with a small difference between groups at 3 DIM (eucalcemic: mean = 4.67 µg/mL, 95% CI = 4.02 to 5.42 µg/mL; dyscalcemic: mean = 7.91 µg/mL, 95% CI = 6.49 to 9.63 µg/mL) that became larger at 4 DIM (eucalcemic: mean = 4.88 µg/mL, 95% CI = 4.22 to 5.64 µg/mL; dyscalcemic: mean = 10.79 µg/mL, 95% CI = 8.84 to 13.17 µg/mL). Our work supports the hypothesis that dyscalcemia and inflammatory activity are associated in dairy cows under naturally occurring postpartum conditions. While the causal structure of this relationship remains unknown, improved understanding of inflammation and dyscalcemia may provide insight into mechanisms by which some cows experience maladaptation during the early postpartum period.

Emergent Properties of the Periodic Anderson Model: A High-Resolution, Real-Frequency Study of Heavy-Fermion Quantum Criticality

We study paramagnetic quantum criticality in the periodic Anderson model (PAM) using cellular dynamical mean-field theory (CDMFT), with the numerical renormalization group (NRG) as a cluster impurity solver. The PAM describes itinerant c electrons hybridizing with a lattice of localized f electrons. At zero temperature, it exhibits a much-studied quantum phase transition from a Kondo phase to a Ruderman-Kittel-Kasuya-Yosida (RKKY) phase when the hybridization is decreased through a so-called Kondo breakdown quantum critical point (KB QCP). There, Kondo screening of f spins by c electrons breaks down, so that f excitations change their character from somewhat itinerant to mainly localized, while c excitations remain itinerant. Building on , which interpreted the KB transition as an orbital-selective Mott transition, we here elucidate its nature in great detail by performing a high-resolution, real-frequency study of various dynamical quantities (susceptibilities, self-energies, and spectral functions). NRG allows us to study the quantum critical regime governed by the QCP and located between two temperature scales, TFL&lt;TNFL. In this regime, we find fingerprints of non-Fermi-liquid (NFL) behavior in several dynamical susceptibilities. Surprisingly, CDMFT self-consistency is essential to stabilize the QCP and the NFL regime. The Fermi-liquid (FL) scale TFL decreases toward and vanishes at the KB QCP; at temperatures below TFL, FL behavior emerges. At T=0, we find the following properties. The KB transition is continuous. The f quasiparticle weight decreases continuously as the transition is approached from either side, vanishing only at the KB QCP. Therefore, the quasiparticle weight of the f band is nonzero not only in the Kondo phase, but also in the RKKY phase; hence, the FL quasiparticles comprise c f electrons in both phases. The Fermi surface (FS) volumes in the two phases differ, implying a FS reconstruction at the KB QCP. Whereas the large-FS Kondo phase has a two-band structure as expected, the small-FS RKKY phase unexpectedly has a three-band structure. We provide a detailed analysis of quasiparticle properties of both the Kondo and, for the first time, also the RKKY phase and uncover their differences. The FS reconstruction is accompanied by the appearance of a Luttinger surface on which the f self-energy diverges. The volumes of the Luttinger and Fermi surfaces are related to the charge density by a generalized Luttinger sum rule. We interpret the small FS volume and the emergent Luttinger surface as evidence for f-electron fractionalization in the RKKY phase. Finally, we compute the temperature dependence of the Hall coefficient and the specific heat, finding good qualitative agreement with experiments. Published by the American Physical Society 2024

Augmenting Density Matrix Renormalization Group with Clifford Circuits

Augmenting Density Matrix Renormalization Group with Clifford Circuits

Efficient Simulation of Inhomogeneously Correlated Systems Using Block Interaction Product States.

The strength of the density matrix renormalization group (DMRG) in handling strongly correlated systems lies in its unbiased and simultaneous treatment of identical sites that are both energetically degenerate and spatially similar, as typically encountered in physical models. However, this very feature becomes a drawback when DMRG is applied to quantum chemistry calculations for large, realistic correlated systems. This is because entangled orbitals often span broad ranges in both energy and space, with their interactions being notably inhomogeneous. In this study, we suggest addressing the strong intrafragment correlations and weak interfragment correlations separately, utilizing a large-scale multiconfigurational calculation framework grounded in the block interaction product state formulation. The strong intrafragment correlation can be encapsulated in several electronic states located on fragments, which are obtained by considering the entanglement between fragments and their environments. Moreover, we incorporate non-Abelian spin-SU(2) symmetry in our work to target the desired states we interested with well-defined particle number and spin, providing deeper insights into the corresponding chemical processes. The described method has been examined in various chemical systems and demonstrates high efficiency in addressing the inhomogeneous effects in strong correlation quantum chemistry.

Relativistic BEC extracted from a complex FRG flow equation

Abstract Based on the functional renormalization group (FRG) under the local potential approximation, we analyze the Bose-Einstein condensation (BEC) in the relativistic complex scalar theory. This framework leads to a complex flow equation of the effective potential, even with the well-known Litim regulator. In order to evaluate the condensate from such a complex effective potential, we impose a condition between chemical potential and mass, analogously to those in the free theory or the mean field theory. We elucidate that for the strongly (weakly) coupled theory, the phase diagrams computed from the FRG are more (less) deviated from that under the mean field approximation. This result implies that quantum fluctuations strongly affect the nonperturbative formation of the BEC.

CFTD from TQFTD+1 via Holographic Tensor Network, and Precision Discretization of CFT2

We show that the path integral of conformal field theories in D dimensions (CFTD) can be constructed by solving for eigenstates of a renormalization group (RG) operator following from the Turaev-Viro formulation of a topological field theory (topological quantum field theory) (TQFT) in D+1 dimensions (TQFTD+1), explicitly realizing the holographic sandwich relation between a symmetric theory and a TQFT. Generically, exact eigenstates corresponding to symmetric TQFTD follow from Frobenius algebra in TQFTD+1. For D=2, we construct eigenstates that produce 2D rational CFT path integrals exactly, which curiously connect a continuous-field theoretic path integral with the Turaev-Viro state sum. We also devise and illustrate numerical methods for D=2, 3 to search for CFTD as phase transition points between symmetric TQFTD. Finally, since the RG operator is in fact an exact analytic holographic tensor network, we compute “bulk-boundary” correlators and compare them with the AdS/CFT dictionary at D=2. Promisingly, they are numerically compatible given our accuracy, although further works will be needed to explore the precise connection to the AdS/CFT correspondence. Published by the American Physical Society 2024

Large landscape of 4d superconformal field theories from small gauge theories

We systematically explore the space of renormalization group flows of four-dimensional N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{N} $$\\end{document} = 1 superconformal field theories (SCFTs) triggered by relevant deformations, as well as by coupling to free chiral multiplets with relevant operators. In this way, we classify all possible fixed point SCFTs that can be obtained from certain rank 1 and 2 supersymmetric gauge theories with small amount of matter multiplets, identifying 7,346 inequivalent fixed points which pass a series of non-trivial consistency checks. This set of fixed points exhibits interesting statistical behaviors, including a narrow distribution of central charges (a, c), a correlation between the number of relevant operators and the ratio a/c, and trends in the lightest operator dimension versus a/c. The ratio a/c of this set is distributed between 0.7228 and 1.2100, where the upper bound is larger than that of previously known interacting SCFTs. Moreover, we find a plethora of highly non-perturbative phenomena, such as (super)symmetry enhancements, operator decoupling, non-commuting renormalization group flows, and dualities. We especially identify amongst these fixed points a new SCFT that has smaller central charges ac=63320006832000\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\left(a,c\\right)=\\left(\\frac{633}{2000},\\frac{683}{2000}\\right) $$\\end{document} than that of the deformed minimal Argyres-Douglas theory, as well as novel Lagrangian duals for certain N\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{N} $$\\end{document} = 1 deformed Argyres-Douglas theories. We provide a website https://qft.kaist.ac.kr/landscape to navigate through our set of fixed points.

Block-Correlated Coupled Cluster Theory Based on the Generalized Valence Bond Reference for Singlet-Triplet Energy Gaps of Strongly Correlated Systems.

A block-correlated coupled cluster (BCCC) method based on the triplet generalized valence bond (GVB) wave function (GVB-BCCC) has been implemented for the first time. By introducing several techniques, we have developed a practical and efficient GVB-BCCC code. The GVB-BCCC3 method (with up to three-pair correlation) can be used to deal with strongly correlated (SC) systems with triplet or singlet ground states, allowing singlet-triplet (S-T) energy gaps in the active space of SC systems computationally available. For selected SC systems, our calculations show that GVB-BCCC3 can always provide correct ground-state spin multiplicity as the complete active space configuration interaction (CASCI) or density matrix renormalization group (DMRG). Furthermore, we found that the S-T energy gaps from GVB-BCCC3 are quite consistent with CASCI or DMRG results. This work demonstrates that GVB-BCCC3 is a promising theoretical tool for describing S-T energy gaps within the active space of SC systems with large active spaces.

Initial tensor construction and dependence of the tensor renormalization group on initial tensors

We propose a method to construct a tensor network representation of partition functions without singular value decompositions nor series expansions. The approach is demonstrated for one- and two-dimensional Ising models and we study the dependence of the tensor renormalization group (TRG) on the form of the initial tensors and their symmetries. We further introduce variants of several tensor renormalization algorithms. Our benchmarks reveal a significant dependence of various TRG algorithms on the choice of initial tensors and their symmetries. However, we show that the boundary TRG technique can eliminate the initial tensor dependence for all TRG methods. The numerical results of TRG calculations can thus be made significantly more robust with only a few changes in the code. Furthermore, we study a three-dimensional Z2 gauge theory without gauge fixing and confirm the applicability of the initial tensor construction. Our method can straightforwardly be applied to systems with longer range and multisite interactions, such as the next-nearest neighbor Ising model. Published by the American Physical Society 2024

Optimization of a novel biomimetic vortex generator structure based on cavitation intensity and stability control

Cavitation phenomena in the fields of hydraulic machinery and underwater submersibles have brought numerous negative impacts, such as vibration noise and mechanical damage. To suppress cavitation intensity and reduce the negative effects of cavitation instability, a biomimetic vortex generator (BVG), arranged on the surface of hydrofoils, is proposed in this study. The renormalization group k-ε turbulence model with density correction and the Ffowcs Williams and Hawkings acoustic model are employed. The cavitation intensity and cavitation stability of the BVG hydrofoil at different arrangement densities are analyzed. Cavitation control performance can be enhanced by reducing the spacing between structures on the hydrofoil. However, an excessively high BVG arrangement density may cause large-scale cavities to collapse prematurely, promoting the formation of small-scale cavities. This exacerbates cavitation instability, intensifies high-frequency pressure oscillations, and consequently amplifies noise. To mitigate performance degradation in hydrofoils caused by high-density BVG arrangements, the effects of structural height on the reentrant jet and surface vortices are analyzed. As a result of BVG structural optimization, cavitation intensity is further reduced, and cavitation stability is improved. Compared to the baseline hydrofoil, the time-averaged vapor volume over three cavitation cycles is reduced by 22.68%, the overall sound pressure level at receiver F decreases by 5.7 dB, and the dominant frequency of S3h2 hydrofoil cavitation decreases by 1.87 Hz. Ultimately, the optimization of the BVG structure enhances cavitation stability and significantly reduces high-frequency noise caused by pressure fluctuations on the hydrofoil surface.

A Nonaxial-Type Swirling Cavitating Nozzle for Exploiting Natural Gas Hydrate

Summary Natural gas hydrates (NGHs) have garnered widespread attention in the new energy sector, owing to their efficient and clean combustion properties. NGHs are ice-like substances formed by methane and water under high-pressure and low-temperature conditions, abundantly deposited in seabeds and frozen soil of highlands on Earth. However, the rock shelves of NGH reservoirs are mostly fragile and sparsely colloidal. Traditional mechanical mining methods can easily cause rock-shelf collapses, leading to mining accidents. Long-term indoor experiments and pilot mining projects have shown that cavitating nozzles can provide a feasible solution to the problem of efficient mining of NGHs. To further improve the efficiency of cavitating nozzle mining for NGHs, we have optimized and designed a nonaxial-type swirling cavitating nozzle (NASCN) based on traditional swirling cavitating nozzles (SCNs). Both numerical simulations and indoor experiments have verified the higher mining performance of this nozzle. In the numerical simulation experiments, we analyzed the cavitation performance, erosion performance, and energy consumption characteristics of different cavitating nozzles using the mixture multiphase flow model and the renormalization group (RNG) k-ε turbulence model. In the indoor experiments, we utilized a jet erosion experimental device for NGHs to analyze the erosion effects of different cavitating nozzles on hydrate samples. The results of these experiments indicate that the NASCN reduces energy consumption by 12% compared with traditional nozzles when there is little difference in cavitation performance and erosion performance. Moreover, under similar energy consumption, the NASCN improves erosion efficiency by 35.2% compared with traditional nozzles. These results demonstrate that the NASCN has good application value in the mining engineering of NGHs.